Field of the Invention
The present invention relates to a focus detection apparatus, a method for controlling the same, and an image capture apparatus.
Description of the Related Art
Two methods, namely a phase-difference detection method (phase-difference AF) and a contrast detection method (contrast AF), are widely used as methods for automatic focus detection (AF) for an image capture apparatus. Dedicated AF sensors have conventionally been used in phase-difference AF, but in recent years, similarly to contrast AF, phase-difference AF in which signals obtained from an image sensor are used has also been realized, and is referred to as image plane phase-difference AF, or the like.
The signals read out from the pixels in order to generate one pair of image signals to be used in image plane phase-difference AF correspond to light flux that is incident at a specified angle. There is known to be a technique in which, using this property, signals corresponding to different incidence angles are shifted and added together so as to generate image signals (refocus signals) in a virtual image capture plane, and thereby contrast AF based on the refocus signals is performed (Japanese Patent Laid-Open No. 2013-25246). Also, there are image sensors such as that described in Japanese Patent No. 3592147, in which focus detection pixels for generating a pair of image signals (A image, B image) to be used in image plane phase-difference AF are arranged discretely.
In the conventional technology, which includes the prior art documents, no consideration is given to performing contrast AF as with Japanese Patent Laid-Open No. 2013-25246 in an image capture apparatus using an image sensor in which focus detection pixels are arranged discretely, as in Japanese Patent No. 3592147.
The present invention has been made in view of the foregoing problem in the prior technology and provides a focus detection apparatus, a method for controlling the same, and an image capture apparatus, according to which it is possible to realize precise focus detection using an image sensor that has discretely-arranged focus detection pixels.